This invention relates in general to marine vessels and more particularly to a marine inboard propulsion system.
Marine vessels such as small water skiing boats and the like typically utilize inboard propeller drive propulsion systems. Unlike an outboard type of propulsion drive, the inboard drive system includes a motor within the boat that includes a drive shaft extending through the hull to the stern. The drive shaft drives a propeller. The advantage of inboard drive as opposed to other types of marine propulsion systems is that the rotation of the propeller causes fewer vortex turbulents generated by the propeller at the surface of the water. This permits a rapid start of the boat while allowing a water skier to traverse across a fewer rear wake vortices generated by the propeller without the water turbulents generally associated with other types of marine drives, such as outboard and stern drive systems.
As seen in prior art FIG. 1, one typical implementation of a inboard drive system 10 includes a motor 11 that uses a drive coupling 13 to rotate a drive shaft 15 through a stuffing box 17. As best seen in prior art FIG. 2, the stuffing box 17 is a cylindrical structure that allows the drive shaft 15 to pass though the hull 19 of the boat. The stuffing box 17 generally is a flexible hose or rubber housing 21 sealed by hose clamps 23 or the like. The stuffmg box 17 is typically filled or xe2x80x9cstuffedxe2x80x9d with stuffing rope to prevent water leakage into the boat around the drive shaft 15. Although the stuffing box 17 may be integrally fastened to the hull 19, a user must continually insure that the packing nut 26 and hose clamps 23 are secured tightly so as to prevent water from entering inside the boat hull. Moreover, the stuffing box 17 must be precisely aligned with that portion of the boat""s hull allowing the shaft to pass though. Since the shaft log 22 is fixed into position, any misalignment provides additional friction and wear to the shaft as it passes though the rubber housing 21 and packing nut 26.
In FIG. 3, as the drive shaft 15 extends from the transmission coupling, through the stuffing box 17, to be supported by a strut 25. In some instances the drive shaft 15 may be enclosed within protective oil lubricated cover or tube 27 to prevent water, mud and/or other liquids from entering the enclosure. Alternatively, the drive shaft 15 will extend directly through the strut 25 which provides support for the drive shaft 15 before reaching a propeller (not shown). The strut 25 typically includes a mounting blade 31 which acts to fix the strut 25 at some predetermined position on the hull of the boat. The strut further includes some type of water lubricated bearing (not shown) such as a cutless bushing to allow the drive shaft 15 to spin within the strut 25 using water as a lubricant. Problems typically associated with this type of arrangement include the friction and continual wear of the water lubricated bearing. Over time excessive play can develop within the strut to the extent that the drive shaft will move laterally and/or radially and is no longer held into a fixed position during rotation. Hence, the strut requires continual attention, repair and replacement of the water lubricated bearing to insure the most optimum and efficient transfer of power to the propeller 29 to help reduce the undesired effects of vibration and movement.
In view of these shortcomings in the prior art drive system, the need exists to construct a more efficient means for providing support of drive shaft during its rotation in an inboard drive marine vessel propulsion system. This will insure very little maintenance and an efficient means to transfer power to a marine propeller while aiding in the support of the driveline.
Briefly, according to the invention, there is provided a mounting support for use in an inboard drive marine propulsion system. A center support and rear strut include one or more bearing assemblies and well as a seal at both ends of a support housing for reventing water from entering the support housing. Roller bearings are used to enhance rotational movement of a drive shaft while providing very little or no lateral movement. This greatly reduces wear and maintenance of the mounting support items to provide more efficient and less expensive operation of the marine vessel.